docs: def output_vlan(gandi, vlan, datacenters, output_keys, justify=10):
      """ Helper to output a vlan information."""
      output_generic(gandi, vlan, output_keys, justify)
  
      if 'dc' in output_keys:
          for dc in datacenters:
              if dc['id'] == vlan.get('datacenter_id',
                                      vlan.get('datacenter', {}).get('id')):
                  dc_name = dc.get('dc_code', dc.get('iso', ''))
                  break
  
          output_line(gandi, 'datacenter', dc_name, justify)